"The 21-year-old centre back completed his medical yesterday and officially put pen to paper on his new Liverpool contract this morning," Liverpool said on their website.

"Agger will train with his new team-mates at Melwood today as the Reds prepare for Saturday's Premiership clash with Tottenham."

Agger is the second defender to arrive at Anfield in the winter transfer window after Dutch international Jan Kromkamp.

Liverpool boss Rafael Benitez revealed he has been interested in Agger for long time and said that the player's injury was the reason behind delaying the move.

"Daniel is a player we have been following for a long time. We first spoke to Brondby about the player when we were in Monaco playing the Super Cup final," the Spaniard told Liverpool's website.

"We scouted Daniel for a long time but then he picked up an injury.

"When he returned to fitness we watched his first game back and we knew he was at the kind of level we require."